An offensive and derogatory term refering to native americans. Comes from when the government paid for each 'indian' one killed. Instead of carrying the bodies they would take the scalps to prove they had murdered a native american.
When plural the name of a NFL team from Washington DC
It seems there is a too common belief that the word redskin is not offensive so I dare those who believe that to go try that word out on a native american person and see their reaction.
At a casino on a reservation a customer refered to one of the native american employees as redskin. The customer was shot by that employee. So obviously it is offensive.